1.greatly wind,low noise 2.composition easily,solid durable 3.moveable, air changed well 4.overheat-prevention,more safely size model power frequency watts speed pressure flow rate 16" TB-40C-2 380 50 1,1 2900 160 9500 16" TB-40C-4 380 50 0,75 1450 150 8500 20" TB-50C-4 380 50 1,5 1450 210 11000 24" TB-60C-4 380 50 2,2 1450 270 16300 Certificate : CCC CE ROHS